export default class Recorder {
    constructor(stream, config) {
      //兼容
      window.URL = window.URL || window.webkitURL;
      navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
   
      config = config || {};
      config.sampleBits = config.sampleBits || 16;   //采样数位 8, 16
      config.sampleRate = config.sampleRate || 8000; //采样率(1/6 44100)
   
      this.context = new (window.webkitAudioContext || window.AudioContext)();
      this.audioInput = this.context.createMediaStreamSource(stream);
      this.createScript = this.context.createScriptProcessor || this.context.createJavaScriptNode;
      this.recorder = this.createScript.apply(this.context, [4096, 1, 1]);
   
      this.audioData = {
        size: 0,          //录音文件长度
        buffer: [],    //录音缓存
        inputSampleRate: this.context.sampleRate,   //输入采样率
        inputSampleBits: 16,     //输入采样数位 8, 16
        outputSampleRate: config.sampleRate,   //输出采样率
        oututSampleBits: config.sampleBits,       //输出采样数位 8, 16
        input: function (data) {
          this.buffer.push(new Float32Array(data));
          this.size += data.length;
        },
        compress: function () { //合并压缩
          //合并
          let data = new Float32Array(this.size);
          let offset = 0;
          for (let i = 0; i < this.buffer.length; i++) {
            data.set(this.buffer[i], offset);
            offset += this.buffer[i].length;
          }
          //压缩
          let compression = parseInt(this.inputSampleRate / this.outputSampleRate);
          let length = data.length / compression;
          let result = new Float32Array(length);
          let index = 0, j = 0;
          while (index < length) {
            result[index] = data[j];
            j += compression;
            index++;
          }
          return result;
        },
        encodeWAV: function () {
          let sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate);
          let sampleBits = Math.min(this.inputSampleBits, this.oututSampleBits);
          let bytes = this.compress();
          let dataLength = bytes.length * (sampleBits / 8);
          let buffer = new ArrayBuffer(44 + dataLength);
          let data = new DataView(buffer);
   
          let channelCount = 1;//单声道
          let offset = 0;
   
          let writeString = function (str) {
            for (let i = 0; i < str.length; i++) {
              data.setUint8(offset + i, str.charCodeAt(i));
            }
          };
   
          // 资源交换文件标识符
          writeString('RIFF');
          offset += 4;
          // 下个地址开始到文件尾总字节数,即文件大小-8
          data.setUint32(offset, 36 + dataLength, true);
          offset += 4;
          // WAV文件标志
          writeString('WAVE');
          offset += 4;
          // 波形格式标志
          writeString('fmt ');
          offset += 4;
          // 过滤字节,一般为 0x10 = 16
          data.setUint32(offset, 16, true);
          offset += 4;
          // 格式类别 (PCM形式采样数据)
          data.setUint16(offset, 1, true);
          offset += 2;
          // 通道数
          data.setUint16(offset, channelCount, true);
          offset += 2;
          // 采样率,每秒样本数,表示每个通道的播放速度
          data.setUint32(offset, sampleRate, true);
          offset += 4;
          // 波形数据传输率 (每秒平均字节数) 单声道×每秒数据位数×每样本数据位/8
          data.setUint32(offset, channelCount * sampleRate * (sampleBits / 8), true);
          offset += 4;
          // 快数据调整数 采样一次占用字节数 单声道×每样本的数据位数/8
          data.setUint16(offset, channelCount * (sampleBits / 8), true);
          offset += 2;
          // 每样本数据位数
          data.setUint16(offset, sampleBits, true);
          offset += 2;
          // 数据标识符
          writeString('data');
          offset += 4;
          // 采样数据总数,即数据总大小-44
          data.setUint32(offset, dataLength, true);
          offset += 4;
          // 写入采样数据
          if (sampleBits === 8) {
            for (let i = 0; i < bytes.length; i++, offset++) {
              let s = Math.max(-1, Math.min(1, bytes[i]));
              let val = s < 0 ? s * 0x8000 : s * 0x7FFF;
              val = parseInt(255 / (65535 / (val + 32768)));
              data.setInt8(offset, val, true);
            }
          } else {
            for (let i = 0; i < bytes.length; i++, offset += 2) {
              let s = Math.max(-1, Math.min(1, bytes[i]));
              data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
            }
          }
          return new Blob([data], { type: 'audio/wav' });
        }
      };
    }
   
    //开始录音
    start(param) {
      this.audioInput.connect(this.recorder);
      this.recorder.connect(this.context.destination);
      //音频采集
      let self = this;
      let emptydatacount = 0;
      let startVoice = false
      this.recorder.onaudioprocess = function (e) {
        let data = e.inputBuffer.getChannelData(0)
        let l = Math.floor(data.length/10);
        let vol = 0;
        for(let i=0;i<l;i++){
          vol += Math.abs(data[i*10]);
        }
        console.log("vol",vol);
        //设置开始录音的音量，当达到此音量后开始录音，减少噪音影响
        //如果没有达到音量，会一直等待录音
        if(vol<5){
          if(startVoice){
            emptydatacount ++;
          }
          console.log("emptydatacount",emptydatacount);
          //设置静音停止次数，当录音结束后，在一定次数内自动停止录音        
        //   if(emptydatacount > 10){ 
        //     param.success(self.getBlob());
        //   }
        }else{
          emptydatacount = 0;
          startVoice = true;
          self.audioData.input(data);
        }
      };
    };
   
    //停止
    stop() {
      this.recorder.disconnect();
    };
   
    //获取音频文件
    getBlob() {
      this.stop();
      return this.audioData.encodeWAV();
    };
   
    //回放
    play(audio) {
      audio.src = window.URL.createObjectURL(this.getBlob());
    };
   
    //清理缓存的录音数据
    clear(audio) {
      this.audioData.buffer = [];
      this.audioData.size = 0;
      audio.src = ''
    };
   
    static checkError(e) {
      const { name } = e;
      let errorMsg = ''
      switch (name) {
        case 'AbortError': errorMsg = '录音设备无法被使用'; break;
        case 'NotAllowedError': errorMsg = '用户已禁止网页调用录音设备'; break;
        case 'PermissionDeniedError': errorMsg = '用户已禁止网页调用录音设备'; break;     // 用户拒绝
        case 'NotFoundError': errorMsg = '录音设备未找到'; break;
        case 'DevicesNotFoundError': errorMsg = '录音设备未找到'; break;
        case 'NotReadableError': errorMsg = '录音设备无法使用'; break;
        case 'NotSupportedError': errorMsg = '不支持录音功能'; break;
        case 'MandatoryUnsatisfiedError': errorMsg = '无法发现指定的硬件设备'; break;
        default: errorMsg = '录音调用错误'; break;
      }
      return { error: errorMsg }
    };
   
    static get(callback, config) {
      if (callback) {
        if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
          navigator.mediaDevices.getUserMedia({ audio: true, video: false }).then((stream) => {
            let rec = new Recorder(stream, config);
            callback(rec);
          }).catch((e) => {
            callback(Recorder.checkError(e));
          })
        } else {
          navigator.getUserMedia({ audio: true, video: false }).then((stream) => {
            let rec = new Recorder(stream, config);
            callback(rec);
          }).catch((e) => {
            // Recorder.checkError(e)
            callback(Recorder.checkError(e));
          })
        }
      }
    };
  }
